Marine propulsion.



YASUZO VVADAGAKI, OF SASEBO, JAPAN.

MARINE PROPULSION.

Specification of Letters Patent.

Patented June 4, 1907.

Application jfiled October 29,1906. Serial No- 341,137.

To all whom it may concern.-

Be it known that I, YASUZO WADAGAKI, a subject of the Emperor of Japan, and a citizen of Nojeo village, Kinosaki, residing at Sasebo, in the county of Hizen, Nagasaki Ken, and Empire of Japan, have invented certain new and useful Improvements in Marine Propulsion; and I do declare the following to'be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. This invention relates to improvements in marine propulsion, and consists in the novel construction, combination and arrangement of parts hereinafter described and claimed.

One object of the invention is to provide a propeller with a casing or jacket, which will accelerate the feed of the 'water and confine .it around the propeller, so as to prevent the of the construction illustrated in the accompanying drawings, in which Figure 1 is a vertical longitudinal sectional view through my improved casing or channel for screw propellers; and Fig. 2 is a rear end elevation of the same.

Referring to the drawings by numeral, 1 denotes a screw propeller of suitable form and construction-fixed upon a shaft 2 and dlsposed within a guide casing or jacket 3..

Thls casing 3 is preferably of cylindrical form, and has a longitudinally extending passage-way or channel 4 provided with a contracted central portion 5. This contracted portion 5 is preferably circular in cross section and is of slightly greater diameter than that of the propeller 1, which rotates in it. The portlons of the interior of the channel or passage 4 between its center and its inlet and discharge ends are curved as shown, so that said channel is constantly increasing in diameter from its center toward its ends. This construction thus provides a flared funnel-shaped inlet end (i, which directs the water to the propeller wheel 1 and thereby accelerates the passage of water through thecasing; and it also provides a flared or funnel-shaped discharge end 7, which facilitates the escape of the water. The contracted central portion 5 of the channel not only serves to accelerate the passage of the water therethrough, but also to hold the water to the propeller, and thus prevent the formation of a vacuum around the hub of the wheel and loss of the force, which is usually wasted in forcing the water radially or tangentially.

A ter passing through the contracted part of the channel, the velocity of the water is gradually reduced in proportion in its passage through the rear end of said channel so that the true slip of the propeller will not become excessively high even when it is operating at a very high rate of revolutions. Thus it is seen that disregarding the influence of friction, the force exerted on the-forward side of the contracted portion by the pressure of the incoming water is ahnost entirely halanced by the force exerted on the tail or rear I end of the channel by the pressure of the 'outgoing mass of water with its velocity gradually retarded by virtue of the increasing area of the cross-section and the velocity of the water at the tail end of the channel can and the power required to produce the kinetic energy of the vortex is usually wasted, but when the propeller is provided with the water channel as described above, the centrifugal force of thevortex--wou1d. ..exert aconsiderable amount of forward pressure on the diverging end of the dischar e pipe, thus restoring what otherwise woul have been entirely lost in'the race. The use of contracted water channels serves not only to prevent the force intended for propulsionom being wasted in centrifugal effects in radial or tangentially agitating the surrounding water, but it Wi l materia y increase the forward thrust acting upon the flared part at the discharge end of the channel. Even ICC where there is a slight indication of .a vacuum being produced at the inlet end of the channel, the diminution of the water pressure acting upon the flared part of the inlet end, would indirectly increase the effective thrust in the forward direction. In all cases, of ship propulsion there must be a certain amount of slip imparted upon the water during each revolution of the screw. That is to say, the speed of the water at the discharge end of the channel must be slightly higher than that at the inlet end'and the area of the cross-section at the discharge end should be slightly less than that of the inlet end. l e ductionof speed in the flow of water after it is passed through. the contracted part of the channel, not only facilitates the escape of water therefrom, but it also diminishes the real slip of the screw propeller, thus increasing the ultimate elliciency.

The casing 3 is preferably constructed of two half sections preferably cast from suitable metal. Each of these sections 8, 9 is,

formed in its outer face adjacent to its inner end with an annular channel 10 and an annular flange 11. The two flanges 11 are formed with alined apertures to receive bolts or the like 12, which secure them together. These bolts have their heads and nuts disposed within the channels 10, and the latter are closed by a sectional cylindrical plate or covering 13, which entirely surrounds the casing.

This sectional plate 13 has its edges engaged with seats .14 formed in the sections 8, 9, so that the exterior of said plate is flush with the exterior of said sections. The sectional plate may be secured in these seats by screws or other suitable fastenings 15. Formed in the channel or central opening in the section 8 are integral webs or spokes 16, which support a concentric bearing 17 for the propeller shaft 2. Two of these spokes or webs 16 are preferably provided and they extend vertically. The casing 3 may be mounted upon the bottom of the boat in any suitable manner, but as here shown it is provided with bracket arms 18, which support it from one side of the bottom or stern of the boat. Thesefarms 18 are formed integral with'the section 8 of the casing and are preferably 'a'rranged at right angles to each other. It will, of course, be understood that two of these casin s as here shown are provided upon each boat, one upon either side or as many as maybe required according to the circumstances.

' The operationand advantages of the invention will be readily understood from the foregoing description, taken in connection with the accompanying drawings. It will be seen that when the vessel moves forwardly, the water will be fed to the propeller at a greater speed thanthat of the boat owing to the flared or funnel-shaped inner end 6 and the contracted portion 5 of the channel. After the water passes the contracted part of the channel its speed or velocity is gradually reduced owing to the flare of the discharge end, 7 of the channel, but the water is su'flicientl y confined to prevent the formationof a vacuum around the hub of the propeller wheel and the loss of the force usually wasted in agitating the surrounding water and forcing it radially or tangentially as previously explained.

Various changes in the form, proportion and the minor details of construction may be "resorted to without departing from the principle or sacrificing any .of-"the advantages of this invention, as defined by the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters-Patent, is

1. The combination with a screw propeller, of an elongated casing surrounding said propeller and having outwardly flared inlet and discharge ends gradually converging toward the middle with a smooth running curve, the propeller being disposed in said contracted middle portion with theflared ends extended on opposite sides thereof and gradually eonverging from said propeller in opposite directions in a smooth running curve whereby the velocity of the water is gradually reduced .in proportion in its passage through the rear end of the channel so formed to prevent the true slip of the propeller from becoming excessively high when operating at a hight rate of revolutions.

2. The combination with a screw propeller,

of a casing having a channel provided with a contracted central portion in which the propeller rotates, said caslng com rising sectlons formed wlth annular channe s and annular radially extending'apertured flanges, bolts' passed through the apertures in said flanges and uniting said sections, a sectional plate secured in seats upon the exterior faces of said casing sections and closing the annular channels therein, a bearing for the propeller shaft supported concentrically in one of said sections by webs formed integral therewith,

and integral attaching brackets formed, upon the lastmentioned casing section, substantially as shown and described.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses. I

' YASUZO WAD AGAKI. Witnesses:

' ISUUEZO Snroro,

ENASUKE OKADA.

IIO 

